Refrigerating apparatus



Patented July `12, 1932 UNITED STATES PATENT IOFFICE WARREN H. F. scrmlEDrNe, or DAYTON, omo, AssIeNon To TRIGI'DAIRE CORPORA- TION, or DAYTON, OHIO, A CORPORATION or DELAWARE REFRIGERATING- APARATUS Application med April 29,

The presentV invention relates to refriger-v ating apparatus and more particularly to closed cycle with the refrigerant.

Heretofore in refrigerating systems of the lcompression typetrouble has been experienced because oil employed to lubricate operating parts of the system has accumulated 1o .on the walls and on topof the liquid refrigerant within the evaporator. This accumulation of oil on the'walls and within the evaporator becomes very viscous, as the temperature of the evaporator is reduced, and forms a'thick layeror blanket of the refrigerant which hinders or retards evaporation of the liquid refrigerant contained in the evaporator.

An object of the present invention is to provide an evaporator of a refrigerating system with means which utilizes the difference in pressure 'created therein for its operation to agitate the liquid refrigerant and destroy the blanketing effect of the layer oflubricant. t

Another object of-fthe invention is to provide means within an evaporator which will.

agitate liquid refrigerant beneath a layer of lubricant ioating thereon during each cycle of operation of a refrigerant liquefying unit operatively connected with the evaporator.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawing, whereina pre@ ferred form of the present invention is clearly shown.v

In the drawing: A f

Fig. 1 is a vertical section through a portion of an evaporator having my invention embodied therein and having a refrigerating system shown diagrammatically adapted to4 be connected with the evaporator; and

Fig. 2Ais an enlarged sectional view of a portion of the evaporator taken on the line For the purpose of illustrating the present invention I have shown in Fig. 1 a compressor-condenser-expander type of refrigerating system having an evaporator 10 .1931.'`Seria1 No. 533,758. i

shown in sectionl on a large scale and includ-` ing connectionsI 11 and 12 for operatively connectmg the evaporator with the system.

In addition to the evaporator the system inn cludes a compressor 13, a condenser '14 and a reservoir or liquid refrigerant tank 15. Refrigerant. vapor is withdrawn Vfrom the evaporator 10 through the vapor Or low pressure conduit 16 and' is liqueed in the condenser 14 and returned 1to the evaporator Ithroughthe liquid or highl pressure conduit 1 7. Thecompressor is operated by a mot-or 18 controlled by an automatic switch 19 which may be actuated .in response to the refrigerating demand, for example by a pressure-responsive device 21 connected to the low pressure conduit 16. It is obvious, in systems of the type disclosed, to Lstate that the pressureresponsive Vdevice 21 which actuates the switch 19 for controlling the electric circuit to the-motor is adjusted to operate between certain pressure limits. Since pressures and temperatures of the refrigerant increase or decrease uniformly it is apparent that the device 21 is adapted to maintain certain predetermined tempera'ture limits within the evaporator of the system.

At the beginning of operation of the system the period of time between starting of the motor and compressor and stopping thereof is referred to as they on phase of a cycle of operation of the refrigerant liquefying unit. Theperiod of tim'e between two successive operating periods or on phases7 of the refrigerant liquefying unit is referred to as an olf phase of a cycle of operation of the unit. Thus it is apparent that while the system is in operation to produce refrigeration,

the refrigerant liquefying unit is cyclically liquid refrigerant, and a plurality of duct-s- 25 depending from the header 24 -for circulating refrigerant toa point remote from the -reservoir'such for example to a lower header 25a. The liquid refrigerant indicated at 26 'is kept at aconstantlevel 27 by avalve'28,l

which controls a liquid refrigerant inlet openis supplied to the evaporator through the inlet connection lland the vapor or refrigerant is withdrawn through the con- -nection l2'y connected to the vapor conduit 165.

The apparatus, or system, as generally described above is lubricated by placing a quantity of oil in the crankcase of the compressor and depending upon the splashing of rotating parts to distribute oil throughout the compreor. Some of the oil is; dissolved in the refrigerant and some of the oil is niechanically pumped by the compressor tothe condenr and reservoir and eventually to the evaporator. A The oil in separating by gravityfrom the refrigerant in the evaporator forms globules which adhere to the walls thereof and tend to remain stationary- These globules of oil form a layer of insulation between the liquid refrigerant in the evaporator and the Walls thereof whi ch insulation retards the conduction of heat from the evaporator Wall to refrigerant contained therein and consequently evaporation of the refrigerant is also retarded. Finally after the refrigerant absorbs suicicnt heat to cause its evaporation a disturbance occurs in the evaporator and the globules f oil are to the top of the liquid refrigerant. The refrigerant continues to boil olf in the evaporator, leaving the oil, which .collects ina layer of fromA y2 to ity thick on top of the refrigerant. layer of oil on top of the refrigerant in the evaporator becomes more viscous as the ternvperature of the evaporator is reduced and forms a heavy blanket on top of the refrigerant, the effect of which must be destroyed before evaporated refrigerant can enter the space above the oil so as to aect the pressure responsive device which controls the and stopping of the motor and comprcor.

This collection or accumulation of oil in the evaporator is particularly harmful when. the system is used to refrigerate an ice cream cabinet or the like, wherein very low temperatures are desired to be maintained. Under such conditions within the evaporator of the system the compressor will be operated frequently and only for short intervals of time, y

thus causing short operating cles of the compressor. These short cy of the compreor are caused by thecompressor creati lng a suction in the low pressure conduit 16 and in the space above the liquid level the header 24 of the evaporator, suicient to cause the pressure-responsive device -21 to actuate the automatic switch 19 and break the electric circuit to the motor 18, this stopping the compressor, without breaking up the layer of oil inthe evaporator, thereby prevenh'ng liquid refrigerant below the layer, of oil fran vaporizing. Obviously such short Leccese cycles of the compressor will continue for awhile and the evaporator will not be reduced to the tcm rature atl which the pressure-responsive vice21hasbecnsettomaintain Consequently the vmotor which drives the compressor is stopped before the refrigerant vaporizcs and therefore the detemperature will not be maintained. During these short cycles, the refrigerant rises and consequently the pressure increases 'below the oil. this pressure increases to a point sncient to break through the oil blanket, a violent ebullition or explosion causing a large of liquid refrigerant to flow into the outlet of the evaporator.

During short operating cycles of the compressor, as hereiubefore described, it is obvious that the layer or blanket of lubricant floating on the liquid refrigerant the evaporator will cause a pressure differential in the evaporator. This pressure differential caused the weight of the lubricant together with its and its adhesion to walls of the evaporator. This inherent characteristic is commonly referred to as the static headD lof the lubricant. Such pressure dilferential permits the space in the evaporator above the layer of oil to reduced, by suction of the compressor, considerably more than the atic pressuren of the liquid refrigerant below the oil. Under normal conditiors, with a minimum amount or of slayer of oil in the evaporator, thispressmc diferentialisnotasgreat-as under abnormal conditions when a large IUI or thick layer of oil is contained in the evaporator. However, under all conditions', when the compressor operates, there is a sucient presmre differential to cause the pressure responsive device to actuate and stop operation of compressor before the pressure 1s tially eqnnhzed throughout the entire interior of the evaporator. Thusthelayerofoilcreatesalagofcomiderable extent in evaporation of the refrigerant unless the refrigerant is agitated during the opera of the compressor so that the moycd. Thislagorretardationofrefrigerant evaporating from the body of liquid refrigerantinanevuporator causestherefrigerant which vaporins to accumulateandremainbclowtheoiluntila-pressuresukient tobreaktbroughtheheavyviscolxyer'of oiliscreatcd. iledreirigcnntbmeaththeoihupmlneakingtbroughtheoihcaliquidre-igunnt outktleadingfromtheevlpontor. Th'

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tor,andrendcrsthesystcminekiult Y Vlllyinvcniiolmisdirectedtoasystullin hichtbedilelminauindand phase belfcct-oftbeoilisdetobesp'vlaslledintotherefrigerantY l sure differential within the evaporator, for

causing evaporation of the liquid refrigerant during operation of the compressor. By causing. vaporization of 'refrigerant beneath the oil in an evaporator, during the operating phase.' of each cycle of the ,"compressor.

pressures and consequently temperatures throughout the entire interior of the evaporator will be substantialiy equalized. Thus, the pressure responsive device which actuates the electric switch to start and stop the motor connected with the compressor will be rendered more efficient for controlling cyclical operation of the system between certain definite pressures and the effect of the oil as heroinbefore pointed out will be destroped` thereby rendering the evaporator suitable for maintaining a more constant and uniform temperature. Also by agitating liquid refrigerant within an evaporator, during each cycle of the refrigerant liquefying unit, evaporated refrigerant will be prevented from accumulating below the layer of oil and short operating cycles of the compressor and thereforesplashing of liquid refrigerant into the out et of the evaporator will be eliminated.

Referringnow to Fig. 1 I have provided means to destroy the .blanketing effect of lu`- bricant foating on liqu-id refrigerant in an evaporator for causing the evaporator to maintain a. substantially constant temperature. This means includes a flexible disc or diaphragm 40 sealed in any suitable manner to a circular shaped relatively fiat plug v41 which plug is screw-threaded into a wall of the header 24 of the evaporator 1 0. 'Diaphragm 40 has a member 42 soldered thereto for receiving one one of ay rod 48 which rod extends downwardlytherefrom, through the layer of' oil inthe evaporator, and into the lower portion of the body of' liquid refrig erant 26 in one of the ducts 25 of the 'evaporator 10. The rod 43 has a plurality of discs or fins 44 secured thereto and extending outwardly therefrom but spaced from the inner wall of duct 25. Rod 43 also has one or more discs or fins 45 securedthereto and extending outwardly therefrom for loosely engaging the interior wall of a duct 25. -The fins or discs 45 serve -as a guide forV the rod,43 so that its operationor vertical movement will,

not be prevented. Flow of refrigerant past the. discs 45 is permitted through openings 46 provided therein. Plug 41 which carries the diaphragm 40 includes a closed chamber 48,

of any suitable size, which preferably con- .tains air sealed therein at atmospheric pressure. Diaphragm 40 has-one of its sides fre? 'sponsive to conditions within thechamber 48 i and its other side responsive to conditions or pressure within the evaporator 10. A gasket 49 interposed between ,the plug 41 and the wall of header 24 prevents leakage of refrigerant at this point. Withcountersunk openings 51 adapted to receive a suitable wrench vfor tightening the plug 4l in position and for loosening the plug from the header 24 in order toi remove the diaphragm 41 and rod 43 secured thereto from f uum or suction pressure created by the comf pressor 13 will reduce the pressure exerted on one'side 'of the diaphragm and cause it to `move or to be snapped, into the position shown bythe dotted lines in Fig. 1 of the drawing sometime during operation of the compressor, preferably and for the purpose of rendering the, device infallible in its operation, just prior to the time suction pres- .sure increases to a point sufficient to effect the pressure responsive device 21 to stop the compressor.'

This preference permits a more rugged construction of thechamber 48 and diaphragm 40 so that the diaphragm can be actuated between a widerrange of pressure. The snapping or movement of the diaphragm '40 causes rod 43 ,connected thereto to be moved and also the discs or fins 44 and 45 securedto the rod. It is obvious that this snap action or movement of the discs 44 and 45 will agit-ate the refrigerant contained in the evaporator 10, causing 'evaporation thereL of and consequently the blanketing efi'ect'of the layer of oil above the refrigerant will be dest-ryed. Furthermore, such disturbances cause pressures Aboth above and below the llayer of oil in the evaporator to be substan- The plug 41 is provided tially equal, thereby insuring that the com- Y pressor will not be stopped before the evaporator has been reduced to the desired lowv pressure and consequently temperature.

porized refrigerant below the layer of oil inv the evaporator isalso prevented from accumulating, therefore violent ebullition of the liquid refrigerant is prevented and uniform evaporation of the refrigerant occurs, thus eliminating splashing of liquid refrigerant into the gaseous refrigerant outlet ofthe evaporator. Y e

' After the pressure Within the evaporator, below 'and above the layer of oil on the liquid refrigerant' therein, has been substantially equalized and the compressor creates a sufficientfsucti'on .pressure to effect the pressure responsive device 21 to stop, operation'of the compressor,pressure will then increase within the evaporator, due to evaporation of liqpheric pressure, it may however be desirable,

to partially evacuate the chamber 48 of its air content or tocharge the chamber with a suitable volatile fluid. For this purpose I have provided a tube 53 secured'to the plug 41 which tube serves as a means for evacuating or filling the chamber 48 with a fluid if desired. After partially evacuating or lilling the chamber 48, this tube 53 is adapted to be bent and soldered so as to seal the chamber. It is to be further understood that'the rodA 43 and discs 44 and 45 secured thereto must be constructed of material which is light in weight so as to prevent their weight from impairing operation of the diaphragm 41 utilized to actuate' the rod 43. However, it may be desirable to provide some well known means, such as springs or the like for example, for counterbalancing the weightv of rod 43 and the discs secured thereto.

From the foregoing it is apparent that I have provided an improved apparatus which is sure in its operation and which functions eiiiciently when the system is operating to maintain a very low temperature, which low temperature increases the viscosity of lubricant, while at the same time providing means for preventing the lubricant from retarding evaporation of liquid refrigerant in the evaporator by destroying the oil blanket priorA to the cut-out setting of the switch so that vaporization will take place every time the compressor `is started.l With the hereinbefore enumerated difficulties eliminated, evaporators employed to produce very low temperatures are rendered more eflicient for maintaining a constant range of temperature. Likewise the life of the compressor and its operating motor is prolonged by the prevention of the heretofore described -short operating cycles thereof.

While the form of embodiment of the invention as herein disclosed constitutes a preferred form, it is to be understood that other forms might be adopted, all coming within the scopeA ofthe claims which follow.

What is claimed is as follows:

1. In a refrigerating system' of the type in which a body of liquid refrigerant is maintained in an evaporator and in whichl a layer of lubricant ioats on the liquid refrigerant in the evaporator, the combination of an evaporator, means for supplying liquid re- 1,soo,sas

frigerant to and for withdrawing gaseous refrigerant from said evaporator, means for starting and stopping said first named means, means for'agitating the liquid refrigerant in said evaporator to destroy the blanketing effect of the lubricant, said last named means including a' portion disposed below the liquid level in said evaporator, and means responsive during each cycle due to the cyclical operations of said first named means for actuating said portion of said last named means.

2. In a refrigerating system of the type in which a body ofliquid refrigerant islmaintained in an evaporator and in which a layer of lubricant ioats on the liquid refrigerant in the evaporator, the combination ofl an evaporator, means for supplying liquid refrigerant to and for withdrawing gaseous refrigerant from said evaporator, means for starting and stopping said first named means, means for agitating the liquid refrigerant in said evaporator to ...destroy the blanketing effect of the lubricant, said last named means including a portion disposed below the liquid level in said evaporator, and means responsive during the latter part' of the operating phase of each cycle of said-first named means for actuatingsaid portion of said last named means. I

' 3. In a refrigerating System of the type in which a body of liquid refrigerant is maintained in an evaporator and in'which a layer of lubricant ioats on the liquid refrigerant in the evaporator, the combination of an evaporator, means for supplying liquid refrigerant' to and for withdrawing gaseous refrigerant from said evaporator, means for starting and stopping said first nalned means, means for agitating the liquid refrigerant in said evaporator to destroy the blanketing effect ofthe lubricant, said last named means including a portion disposed below the liquid level in said evaporator, and means responsive during the operating phase of each cycle, of said first named means for actuating said portion of said last named means.

4. In a refrigerating system of the type in which a body of liquidaefrigerant is maintained in an evaporator and in which a layer of lubricant floats on the liquid refrigerant ,in the evaporator, the combination of an evaporator, means for preventing liquid refrigerant from rising above a predetermined level in said evaporator, means in addition'to said first named means for agitating the liquid refrigerant in said evaporator to destroy the'blanketing eHect of the lubricant, said second named means including a portion disposed below the liquid level in said evaporator, and means responsive to -conditions within said evaporator for actuating said portion of said agitating means.

5. In a refrigerating system of the type in which a body of liquid refrigerant is mainfrigerant from rising above a predetermined level in said evaporator, means in additionto sald first named means for agitatmg the liquid refrigerant in said evaporator to destroy the blanketing effect of the lubricant, said second named means including a portion disposed below the liquid level in said evaporator, and means responsive to pressures Within said evaporator for actuating said portion of said agitating means.

6. In a refrigerating system of the typein which a body of liquid refrigerant is maintained in an evaporator and in which a layer of lubricant floats on the liquid refrigerant in the evaporator, the combination ofv an evaporator, means for preventing liquid refrigerant from rising above a predetermined level in said evaporator, means in addition to said first named means for agitating the liquid refrigerant in said evaporator to destroy ythe blanketing'eii'ect of the lubricant, said second namedmeans including a portion disposed below the liquid level in said evaporator, and means for actuating said portion of said agitating means.

7. In a refrigerating system of the type in which a body of liquid refrigerant is maintained in an evaporator and in which a layer of lubricant oats .on the liquid refrigerant in the evaporator, the combination of an evaporator, means for preventing liquid refrigerant from rising above a predetermined level in said evaporator, means in addition to said first named means for agitating the liquid refrigerant 4in said evaporator to destroy the blanketing effect of the lubricant, said second named means including a portion disposed below the liquid level in said evaporator, and a movable member connected with said portion of said agitating means for ac.

tuating the same, said member being moved in response to conditions withinsaid evaporator.

8. In a refrigerating system of the type in which a body of liquid refrigerant is maintained in an evaporator and in which a layer of lubricant floats on the liquid refrigerant in the evaporator, the combination of an evaporator, means for preventing liquid rerefrigerant from rising above a predetermined level in said evaporator, means in addition to said first named means for agitating the liquid refrigerant in said evaporator to destroy the blanketing effect of the lubricant, said second named means including a portion disposed below the liquid level in said evapoator,'and a snap acting diaphragm connected with said portion of said agitating means n for actuating the same, said diaphragm being evaporator.

moved in response to conditions within said 9. In a refrigerating system of the type in which a body' of liquid refrigerant is maintained in an evaporator and in which a layer f of lubricant floats on the liquid refrigerant in they evaporator, the combinatior of an evaporator, means for preventing liquid refrigerant fromrising above a predetermined -level in said evaporator, means in addition to said rst named ,means for agitating the liquid refrigerant in said evaporator to destroy the blanketing effect of the lubricant, said second Fnamed means including a portionv disposed below the liquid level in said evaporator, and a snap acting diaphragm connected with/said portion of said agitating means for actuating the same, said diaphragm being moved in response to pressures'within said evaporator.

l0. In a refrigerat-ing system of the typel in which a body of liquid refrigerant is maintained in an evaporator and in which a layerA of lubricant floats on the liquid refrigerant in the evaporator, the combination of an evaporator, means for supplying liquid refrigerant to and for withdrawing gaseous refrigerant from said evaporator, means fory starting and stopping said first named means,

' means for destroying the blanketing effect of the lubricant floating on the liquid refrigerant insaid evaporator, said last named means including a vertical `member extending through the layer of oil and into the liquid refrigerant, and means connected with said member and responsive during each cycle due tothe cfyclical operations of said first named means'V or actuating said member to agitate the liquid refrigerant in said evaporator.

11. In a refrigerating system of the type in which a body of liquid refrigerant is maintained in an eva orator and in which a layer of lubricant oats on the liquid refrigerant in the evaporator, the combination of van evaporator, means for supplying liquid refrigerant to and for withdrawing gaseous refrigerant from said evaporator, means for starting and stopping said first named means, means for destroying the blanketing effect of the lubricant floating on the liquid refrigerant in said evaporator,

vsaid last named means including a vertical member extending through the layer of oil and into the liquid refri erant, ,and means connected with-said mem er and responsive during each cycle due to the cyclical operations of said first named means foraotuating said member, said member having a plurality of discs secured thereto for agitating liquid refrigerant in said evaporator upon movement of themember.

12. In a refrigerating system of the type lin which aH body of liquidrefrigerant is maintained in an evaporator and in which a layer of lubricant floats on the liquid' refrigerant in the evaporator, the combination of an evaporator, means for supplying lll y liquid refrigerant to and for withdrawing gaseous. refrigerant from said evaporator, means for starting and stopping said first named means, means for destroying the blanketing effect of the lubricant ioating on the liquid refrigerant in said evaporator, said last named means including a vertical member extending through the layer of oil and into the liquid refrigerant, and means connected with said member and responsive during the latter part ofthe operating phasve of eachvcycle of said iirst named means for actuating said member to agitate the liquid refrigerant in said evaporator.

13. In a refrigerating system of the type s in which a body lof liquid refrigerant is maintained in an evaporator and inwhich a layer of lubricant floats on the liquid re- 'frigerant in the evaporator, the combination of' an evaporator, means for supplying liquid refrigerant to and for withdrawing gaseous refrigerant from said evaporator, means for starting and stopping said first' named means,` means for destroying the blanketing effect of the lubricant floating on the liquid refrigerant in said evaporator, .said last named means including: a vertical member extending through the layer of oil and into the liquid refrigerant, and means connected with said member and responsive during the operating phase of each cycle of said first named means for actuating said member to agitate the' liquid refrigerant in said evaporator. Y

14. In a refrigerating system of the type in which a. body of liquid refrigerant is maintained in an evaporator and in which a layer of lubricant floats on the liquid refrigerant in the evaporator, the combination of an evaporator, means for supplying liquid refrigerant to and for withdrawmg gaseous refrigerant from said evaporator, means for starting and stopping said first named means, means for destroying the blanketing eect of the lubricant in said evaporator, said last named means includinga vertical member extendin through the layer of oil and into the liquid refrigerant, and means connected with `said member and responsive during the operating phase of each cycle of said first named means for actuating said member, said member having a plurality of discs secured thereto vand extending outwardly therefrom for agitating liquid refrigerant 1n said evaporator upon movement of the member.

' In testimony whereof nature.

-WARREN H. F. SCHMIEDING.

I hereto aix my sig- 

